Electronic governor for injection-type internal combustion engines

ABSTRACT

An electronic governor for injection-type internal combustion engines, having a fuel oversupply mechanism for facilitating the starting up of the engine, a speed regulation setting circuit, an electromagnetic fuel control mechanism of movable type and a means for providing an &#39;&#39;&#39;&#39;ungleich&#39;&#39;&#39;&#39; action, in which an output DC voltage proportional to the rotation speed of engine generated by a DC voltage generating circuit and an unbalance output voltage relative to the position of the fuel supply lever of the engine from a bridge circuit are comparated by a voltage comparator circuit, the output of the comparator circuit is fed to an amplifying circuit, and a fuel control rod of the fuel control mechanism is actuated by the output signal from the amplifying circuit.

United States Patent Ohtani et a1.

[451 Jan. 25, 1972 of Higashi; Todomu Kakillma, Fukuoka, all of Japan Diesel Kiki Kabushiki Kaisha, Tokyo, Japan [22] Filed: May 27,1970

[21] Appl.No.: 40,793

[73] Assignee:

[51] ..B60k 31/00, FOZd 11/10 [58] Field of Search ..123/102, 32 EA; 180/105 E [56] References Cited UNITED STATES PATENTS 3,543,73942/1970 Mennesson ..123/32EA 3,407,793 10/1968 Lang ..123/102 3,060,602 10/1962 Buttenhoff ..180/105 E 3,201,647 8/1965 Prescott ..l80/l05 E 3,124,693 3/1964 Peras ..l80/l05 E 3,476,205 11/1969 Kato.... .....l23/l02 3,400,776 9/1968 Smith .180/105 R 2,856,910 10/1958 Goodridge ..l23/l19 Primary Examiner-Mark M. Newman Assistant ExaminerCort Flint Attorney-Larson, Taylor and Hinds 5 7] ABSTRACT An electronic governor for injection-type internal combustion engines, having a fuel oversupply mechanism for facilitating the starting up of the engine, a speed regulation setting circuit, an electromagnetic fuel control mechanism of movable type and a means for providing an ung1eich" action, in which an output DC voltage proportional to the rotation speed of engine generated by a DC voltage generating circuit and an unbalance output voltage relative to the position of the fuel supply lever of the engine from a bridge circuit are comparated by a voltage comparator circuit, the output of the comparator circuit is fed to an amplifying circuit, and a fuel control rod of the fuel control mechanism is actuated by the output signal from the amplifying circuit.

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ELECTRON1C GOVERNOR FOR INJECTION-TYPE INTERNAL COMBUSTION ENGllNES This invention concerns the electronic fuel control device for injection-type internal combustion engines.

The drawback in the conventional devices of this kind has heretofore existed in the mechanism for controlling the fuel control rod. With a conventional control device, the controlling force, that is, the force required to actuate the fuel control rod for control purpose is not large enough to ensure the stability of control because it is obtained from the fuel injection pump drive through the medium of speed-controlled eddy current.

The invention is to eliminate the drawback mentioned above, and to introduce an ungleich" characteristic into the operation of the governor, which includes a conventional fuel oversupply mechanism for use during engine starting and a conventional speed regulation setting circuit, in order more effectively to meet the characteristic fuel requirements of the engine.

In order that the invention may be more clearly understood, references will now be made to the accompanying drawings in which:

FIG. 1 is an electrical block diagram showing an electronic governor for injection-type internal combustion engines according to this invention;

FIG. 2 is a circuit diagram showing an embodiment of the electronic governor;

FIG. 3 is a diagram of the characteristic of the voltage ap plied to an electromagnetic fuel control mechanism of the invention;

FIGS. 4 and 5 are a cross-sectional views for illustrating different electromagnetic fuel control mechanisms according to the invention attached to fuel injection pump;

FIG. 6 is a diagrammatic view showing an embodiment of a fuel oversupply mechanism attached to the fuel injection pump; and

FIG. 7 is a graph showing a control characteristic of the electronic governor of the invention.

Referring to FIG. 2, T1T13 are transistors; D1-D4, diodes;

C1-Cl2, capacitors; R1-R34, resistors; VR1 and VR2, variable resistors; L1, a coil; VL, a variable inductance coil; L2, a movable coil in the fuel control mechanism; Tr, a transformer; 1, a positive conductor; 2, a negative conductor. These circuit elements are arranged as follows:

In the same figure, section A is an electromagnetic converter for translating rotating speed into voltage. It is formed with a detector coil 4a and a permanent magnet 4 positioned close to a magnetic body 311 in toothed wheel shape. The magnetic body 3a is coupled to the camshaft 3 of the fuel injection pump. As the body 3a rotates, its teeth or peripheral protrusions move past the magnet 4. Each tooth moves toward the magnet 4 and then away from it. This relative movement repeats itself to induce a voltage in detecting coil 4a on the magnet 4, as body 3a rotates. The induced voltage applies to amplifying circuit B composed of transistor T1, capacitor C1, resistors R1 and R2. From this circuit 13 as an amplified voltage is differentiated by differentiating circuit C having capacitor C2 and resistor R3 and then a trigger pulse signal is delivered. The trigger pulse signal applies to detecting circuit having diode D1. This diode removes positive pulses from the signal. The resulting negative pulse signal enters monostable multivibrator circuit D, composed of transistors T2 and T3, load resistances R4 and R8, bias resistor R6, base resistor R7, speedup capacitor C4, and resistor R5 and capacitor C3 for use in setting the time constant thereby inducing a rectangular waveform whose pulse length is constant. The output signal of this multivibrator D is fed to integrating circuit E composed of resistor R9 and capacitor C5, and emerges from the integrating circuit as a DC voltage proportional to the pulse frequen cy, that is, the value of engine rpm. The DC voltage applies to comparator circuit F, of which more will be said later. In circuit F, transistor T4 is so connected that it becomes conductive when a DC voltage applies to its base and, by conduction, changes its collector voltage. The output voltage of comparator circuit F is amplified by the next amplifying circuit G composed of resistors R13, R11, and R15 and transistor T5. To this transistor T5, variable resistor VR1 for setting the speed regulation is connected. The amplified output signal from circuit G is again amplified by circuit H composed of transistor T8 and resistor R18 and then supplied to movable coil L2 in the fuel control mechanism P shown in FIGS. 4 and 5. This coil and transistor T9 form power-amplifying circuit 1, in which coil L2 is energized with the output of said circuit H.

Apart from the foregoing arrangement, oscillator circuit J, of known type, produces a signal to be supplied to bridge circuit K. The oscillator circuit J is composed of transistor T10, resistors R19, R20, R21 and R22, capacitors cs and C7 and transformer Tr. The oscillator output signal supplied to bridge circuit K serves as a carrier wave. The circuit K is composed of coil L1, resistors R23 and R24 and variable-inductance coil VL. This variable-inductance coil is for use in setting the rotating speed, and is connected to the fuel supply lever, not shown, of the internal combustion engine. The balance in the bridge circuit K changes with the position of the fuel supply lever. A voltage arising from an unbalanced condition of this circuit applies through capacitor C8 to amplifying circuit L comprising transistor T11, bias resistors R25 and R26, capacitor C9, resistors R27 and R28. The amplified output voltage of circuit L is further amplified by the next amplifying circuit M composed of capacitor C10, resistors R29, R30 and R31 and transistor T12, and is forwarded to detector circuit N composed of diode D3 and capacitor C11. The output signal from this detector N is then converted into a DC voltage by smoothing circuit 0 composed of resistors R32 and R33 capacitor C12. The DC voltage so introduced applies through diode D4 to the comparator circuit F connected to the aforementioned integrating circuit E.

Said comparator circuit F is composed. of transistors T13, and T4, resistors R10, R11, R12 and R34. The emitters of these transistors are connected together, through resistor R34, to negative conductor 2, whereas their collectors are separate ly connected to positive conductor 1, the collector of transistor T4 being so connected through a series circuit of resistors R10 and R11. Resistor R12 connects the junction point between R10 and R11 to negative conductor 2. By this arrangement of the comparator circuit, the output voltage of bridge circuit K, arising from its unbalanced state, applies to the base of transistor T13 to make this transistor conductive and causes a current to flow in resistor R31. With this current, emitter voltage on transistor T4 rises relative to the potential of said unbalance and makes transistor T 1 less conductive. In other words, the transistor T4 becomes conductive proportionally to the output voltage of integrating circuit E which is proportional to rotating speed N of said engine. On the other hand, the degree transistor T4 becomes nonconductive proportionally to the unbalance voltage of bridge circuit K, which is determined by the position of the fuel supply lever. Varied positions of this lever are represented by V L1-VL4l in FIG. 3. Thus, the output voltage of transistor T4 is. proportional to the difference between the two voltages from integrating circuit E and bridge circuit K. This output voltage is amplified by circuit G, in which said variable resistor VR1 for setting the speed regulation is provided. As will be shown by the dot line VR1 in FIG. 3, the degree of amplification on this amplifying circuit G may be adjusted by the resistor V R1. By a change in the amplification degree the rate of change (or gradient) of output voltage can be changed for a change in engine speed. Said rate of change determines the speed regulation for the engine. Generally, as small a speed regulation as will avoid engine hunting is preferable. Once resistor VR1 is set to secure the preferred regulation, it is seldom necessary, in actual application, to reposition this resistor. The output voltage of circuit G, as stated above, applies to amplifying circuit H and then to electromagnetic fuel control mechanism P for controlling the engine speed. On the other hand, the DC voltage shunted from the output integrating circuit IE, which is proportional to the rotation speed of engine, is diverted and impressed onto the base of transistor T7 in a downstream side circuit designated as U, whose other elements are diode D2 and resistor R17. The emitter of T7 is connected to the cathode of D2, whose anode is connected to the series amplifying circuit V composed of variable resistor VR2, resistor R16 and transistor T6. Variable resistor VR2 is for use in setting ungleich," whose meaning will be made clear later. The emitter of transistor T6 is connected to the base of transistor T8 in amplifying circuit H. Thus, the DC signal proportional to the rotation speed of engine from the circuit V is amplified by the circuit H, and then is fed to power-amplifying circuit I. On the output of circuit H, therefore, in addition to the unbalance voltage produced in relation to the position of the fuel supply lever, an output voltage proportional to the rotation speed of engine is obtained. This operation is represented by the dot line VR2 in FIG. 3 and provide ungleich" action. Ungleich denotes the action by which the fuel injection quantity is automatically decreased in proportion as an air-intake efficiency of engine cylinder decrease with rising engine speed under full load operating conditions.

Referring now to FIGS. 4 and 5, the electromagnetic fuel control mechanism P is mounted on the fuel injection pump 5 and comprises cylindrical exciting coil P1, annular movable coil L2, inner pole P2 and annular outer pole P3. Movable coil L2 is located between the inner and outer poles. These components are centered on a common axis and enclosed in a case. Movable coil L2 is supported from the fuel-adjusting lever 5a by means of a link member extending through the case. Exciting coil P1 is supplied with exciting current from an external electrical source, not shown, and, when so excited, energizes poles P2 and P3 magnetically. CoilL2 is energized with a control current supplied from the output of said poweramplifying circuit I and, when so energized, induces a force proportional in strength to the magnitude of energizing current and acting in the direction perpendicular to the direction of magnetic field, by Flemings left-hand rule. This force is, mathematically, the product of coil length, flux density of magnetic pole and energizing current. Now, since the source of exciting current for coil P1 is the battery belonging to the engine, a change in the battery voltage would result in a corresponding change in the flux density and hence in the force acting on movable coil L2. Such a change can be avoided by applying to exciting coil Pl a voltage high enough to saturate the flux density, or by substituting a permanent magnet P4, shown in FIG. 5, for the electromagnet composed of coil Pl, poles P, P2 and P3.

In FIG. 6, showing a fuel oversupply mechanism for facilitating the starting up of engine, fuel control rod 5a has a protrusion 5b at its distal portion, and electromagnet 6 is appropriately located to magnetically attract and release stopper 6a. This stopper is urged by spring 6b to bear against said protrusion 5b. Fuel control rod 5a is urged by spring 7 to move in the direction of increasing fuel injection quantity, but is prevented by stopper 6a from so moving. Electromagnet 6 is electrically so associated with the engine starter switch, not shown, that turning on the starter switch automatically closes its circuit to energize its coil. If, for example, the full movable range of fuel control rod 5a up to its full load position is from to 14 mm., at starting of engine, control rod a must be moved farther beyond the 14 mm. limit to say, mm. position so as to inject a much greater quantity of fuel. This is automatically accomplished in the arrangement shown by turning on the starter switch to energize coil 6 and thereby pull stopper 6a away from protrusion 5b. This allows control rod 50 to move to the 20 mm. position under the urging force of spring 7. In other words, an attempt to start up the engine automatically increases the range of control rod movement from 14 mm. to 20 mm. in this example. After firing up the engine, the starter switch is turned off, as is the usual practice, and this turning off of the starter switch deenergizes electromagnet 6 to release stopper 6a and thereby limit the movable range of control rod 50.

The arrangement and actions described in the above will be explained in relation to the control of the engine by referring to FIGS. 3 and 7. Turning on the starter switch energizes electromagnet 6 to disengage stopper 6:: from the protrusion 5b of rod 5a. At this moment, the control current to said electromagnetic fuel control mechanism P will be negligibly small because the engine is not yet running fast enough. Consequently, control rod 5a will move to the oversupply position Qmax under the force of spring 7 to facilitate the firing up of the engine. By turning the starter switch off after firing up will restore the full load point 01" for rod 511 may be determined by the stopper 6a, as explained previously. Suppose that the engine is running steadily at a constant speed, carrying a partial load, with the fuel supply lever, not shown, set at a given position, and let the point 81 in FIG. 7 represent this operating condition. If the partial load is removed, and hence the rotation speed of engine is increased, by the action of converter circuit A, pulse number on monostable multivibrator circuit D increase. As a result, the output voltage of integrating circuit F rises to increase the energizing current supplied from the output of power-amplifying circuit I to movable coil L2. The increased energizing current then causes coil L2 to shift in the direction of decreasing fuel injection quantity, thereby pulling control rod 5a against the force of spring 7 to decrease the injection quantity progressively to curb the rising tendency of engine speed until a state of equilibrium comes into being between engine load and output power. This state of equilibrium is represented by point S2 in FIG. 7. Conversely, if engine load is increased, a series of similar but directionally opposite regulating operations will take place.

When the engine output power is required to be increased, moving the fuel supply lever varies the value of inductance VL in bridge circuit K to reduce the energizing current supplied from the output of power-amplifying circuit I to movable coil L2, thereby making spring 7 overcome the force acting on coil L2 and move fuel control rod 5a in the direction of increasing injection quantity to a position corresponding to point S3 in FIG. 7. If a small speed regulation is required, the resistance of the variable resistor VRl must be lowered. The resultant change in the magnitude of speed regulation corresponds to a shift from solid line VRl to dot line VRl in FIG. 7.

It should be noted that, while the engine speed is rising, two voltages apply to poweramplifying circuit I: one is the output voltage of comparator circuit F and the other is that of amplifying circuit V. By the latter voltage, the point, from which the output voltage of circuit I begins to rise, shifts upward. This upward shift is represented by dot line VRZ in FIG. 3 and constitutes the ungleich action. The ungleich characteristic refers to the gradient of dot line VR2 in FIG. 7. The gradient can be varied as desired by varying the setting of variable resistor VR2 in amplifying circuit V.

It will be apparent from the preceding description that the governor according to this invention includes not only such conventional features as adjustable speed regulation and a fuel oversupply mechanism for facilitating the starting up to the engine but also a new feature of ungleich" action, and provides an electromagnetic fuel control mechanism of movable type making available stable controlling force, all for improved control of the engine in operation.

While the invention has been described with respect to the illustrated embodiments thereof it is to be understood that various changes and modifications may be made without departing from the spirit and scope of the invention, and it is intended, therefore, to cover all such changes and modifications in the appended claim.

What is claimed is:

I. An electronic governor for an injection-type internal combustion system comprising: a DC voltage generating circuit for generating a DC voltage proportional to the speed of rotation of the engine; a bridge circuit including a variable inductance coil located in one arm thereof, an oscillator circuit connected across the input of said bridge, the impedance of said coil being a function of the position of the fuel supply cordance with a desired rate of automatic decrease in the quantity of fuel injected corresponding to the decrease in airintake efficiency of the engine cylinders with rising engine speed under full load conditions; and an electromagnetic fuel control mechanism for controlling a fuel control rod responsive to the output of said amplifier circuit.

4 l 4 ii i 

1. An electronic governor for an injection-type internal combustion system comprising: a DC voltage generating circuit for generating a DC voltage proportional to the speed of rotation of the engine; a bridge circuit including a variable inductance coil located in one arm thereof, an oscillator circuit connected across the input of said bridge, the impedance of said coil being a function of the position of the fuel supply lever of the engine and the unbalance output voltage of said bridge circuit correspondingly being a function of the position of the said fuel supply lever; a voltage comparator circuit for comparing the output voltage of said DC voltage generating circuit with the unbalance output voltage of said bridge circuit; a variable amplification amplifier circuit for amplifying the output of said voltage comparator circuit and including means for varying the amplification of said amplifier in accordance with a desired rate of automatic decrease in the quantity of fuel injected corresponding to the Decrease in air-intake efficiency of the engine cylinders with rising engine speed under full load conditions; and an electromagnetic fuel control mechanism for controlling a fuel control rod responsive to the output of said amplifier circuit. 